You're right, I copied the original puzzle incorrectly. My old eyes have trouble with all those little numbers! I'll go back and try it again and let you know how I do.

A couple of points: As I said earlier, I just started doing these puzzles, so I don't know what you all mean by "invalid" moves or "bifurcating." Sometimes I get to a point where I have to approach the puzzle like a chess game and think through the logical consequences of alternate moves. This doesn't seem any less logical to me than other approaches.

Someone in this thread suggested writing a program to solve puzzles. I'm not a programmer, so I wouldn't have any idea how to do that, and even if I could, it doesn't sound like much fun to me. I'd rather think the puzzles through myself. But, to each his own.

BTW: I'm a person of the female persuasion. My name confuses people, but Terry can be a woman's name as well as a man's name.

I'll get back to you after I've had a go at the puzzle with the correct numbers.
Terry

On further inspection it works out with just the one "invalid" move (by which I mean an arbitrary trial and error choice from among the candidates that has no logic behind it) not two as I suggested.

So the "6" at r9c3 remains as before the "invalid" move. But you then reach a point where you have 47 cells completed and a lot of cells with just the two candidates. There is an xy-chain starting at r1c1 and winding its way round to r5c9 that allows an elimination in r5c1. There may be other chains that have the same effect. This is a much more satisfactory way of proceeding to my purist mind which gives the result that Ms Terry already posted.

This is a good website for collecting together the principal logical techniques and giving them names:

I wonder, someone-somewhere, if it is always the case that the minimum layouts like on the website you talked about need at least one trial and error move. This suggests another question; what is the minimum number of filled cells that produce a puzzle that can be solved by logic alone? That's another one for the mathematicians.

I've answered my own question about whether puzzles with few cells filled in will tend to need trial and error at some point. The following puzzle has only 17 starter cells but can be completed with simple logic.